A switching device is described, for example, in the German patent No. 41 17 031. This switching device has both the function of a rotary switch and a further function, e.g., the function of a pressure-operated switch. In this switching device, disposed in the interior of a housing, standing upright on an inner base surface, is a shaft part upon which a rotary plate is supported having a wiper mounted on it. The wiper is in electrical contact with circuit patterns which are arranged on a supporting plate. The rotary motion of the shaft part causes the wiper to glide over the circuit patterns, whereby contacts can be changed. A tubular, elastic contact member is placed around the shaft part. A manually operated button is moveable around and along a bearing part of the rotary plate, so that when the button is turned, the rotary plate is turned for a switching operation of a rotary switch which is formed by the wiper and a first circuit pattern. In response to an axial movement of the button against a restoring force applied by the elastic contact member, the contact member is actuated by the button like a pressure-operated switch which is formed by a second circuit pattern and the elastic contact member.
It may be that the height of such a switching device is low, but it has a large width and depth, since the circuit patterns are arranged on a flat supporting plate perpendicular to the rotation direction of the rotary switch.
In addition, owing to the shaft arranged centrally in the housing, a central illumination of the rotary switch and of the pressure-operated switch is not possible without difficulty.
An object of the present invention is to further develop a switching device of this type to the effect that, given a compact design and simple assembly, it permits a combination of a rotary potentiometer with a pressure-operated switch, in that the pressure-operated switch is completely decoupled from the rotary potentiometer. The intention is also to permit illumination of the pressure-operated switch and/or the rotary potentiometer in a simple manner.
The embodiment of the rotary potentiometer as a hollow cylindrical form in whose interior the pressure-operated switch is arranged has the particularly great advantage that the pressure-operated switch is completely decoupled from the rotary potentiometer. In this context, in addition to the pressure-operated switch, it is advantageously possible for further elements such as light-conductive elements or even guide elements and actuating elements of the rotary potentiometer to be arranged in the interior of the rotary potentiometer. Here, the relatively large cylindrical interior space of the hollow cylindrical rotary potentiometer permits, purely in principle, the most varied arrangement possibilities of pressure-operated switches, illumination elements, guide- and/or actuating elements of the rotary potentiometer and possible further components such as switching elements, printed circuit boards, and the like.
It is also particularly advantageous that the traversing opening in the rotary potentiometer permits, purely in principle, the most varied actuating variants of the pressure-operated switch which, for example, is secured on a supporting plate arranged below the entire switching devicexe2x80x94even at an angle.
In one advantageous specific embodiment of the present invention, the actuating element of the rotary potentiometer is hollow cylindrical and is rigidly coupled to a wiper which is displaceable on a resistor run by a rotary movement of the rotary potentiometer.
Instead of the rigid coupling, a cardanic coupling can also be provided to thus permit any angular arrangements of the actuating element on the wiper.